Diffuse-type giant cell tumor: clinicopathologic and immunohistochemical analysis of 50 cases with extraarticular disease

Pathology of intra-articular tumours and tumour-like lesions: pearls, pitfalls and rarities from a general surgical pathology practice

Intra-articular tumours are uncommonly encountered in routine practice and may present diagnostic challenges to pathologists. Challenges unique to this site include distinction from more common reactive synovial conditions, which are far more common; histologic variability; superimposed reactive changes; and often, lack of provided clinicoradiological context. This article reviews the pathology of the synovial tumours and tumour-like lesions, including diagnostic pearls, pitfalls and rare entities.

Diffuse-Type Tenosynovial Giant Cell Tumor: What Are the Important Findings on the Initial and Follow-Up MRI?

Tenosynovial giant cell tumor (TSGCT) is a rare soft tissue tumor that involves the synovial lining of joints, bursae, and tendon sheaths, primarily affecting young patients (usually in the fourth decade of life). The tumor comprises two subtypes: the localized type (L-TSGCT) and the diffuse type (D-TSGCT). Although these subtypes share histological and genetic similarities, they present a different prognosis. D-TSGCT tends to exhibit local aggressiveness and a higher recurrence rate compared to L-TSGCT. Magnetic resonance imaging (MRI) is the preferred diagnostic tool for both the initial diagnosis and for treatment planning. When interpreting the initial MRI of a suspected TSGCT, it is essential to consider: (i) the characteristic findings of TSGCT-evident as low to intermediate signal intensity on both T1- and T2-weighted images, with a blooming artifact on gradient-echo sequences due to hemosiderin deposition; (ii) the possibility of D-TSGCT-extensive involvement of the synovial membrane with infiltrative margin; and (iii) the resectability and extent-if resectable, synovectomy is performed; if not, a novel systemic therapy involving colony-stimulating factor 1 receptor inhibitors is administered. In the interpretation of follow-up MRIs of D-TSGCTs after treatment, it is crucial to consider both tumor recurrence and potential complications such as osteoarthritis after surgery as well as the treatment response after systemic treatment. Given its prevalence in young adult patents and significant impact on patients' quality of life, clinical trials exploring new agents targeting D-TSGCT are currently underway. Consequently, understanding the characteristic MRI findings of D-TSGCT before and after treatment is imperative.

CSF1 expression in xanthogranulomatous epithelial tumor/keratin-positive giant cell-rich tumor

"Xanthogranulomatous epithelial tumor" (XGET) and "keratin-positive giant cell-rich soft tissue tumor" (KPGCT), two recently described mesenchymal neoplasms, likely represent different aspects of a single entity. Both tumors are composed of only a small minority of tumor cells surrounded by large numbers of non-neoplastic inflammatory cells and histiocytes, suggesting production of a paracrine factor with resulting "landscape effect," as seen in tenosynovial giant cell tumor. Recent evidence suggests that the paracrine factor in XGET/KPGCT may be CSF1, as in tenosynovial giant cell tumor. We hypothesized that CSF1 is overexpressed in XGET/KPGCT. To test our hypothesis, we performed quantitative real time PCR (qPCR) for CSF1 expression and CSF1 RNAscope chromogenic in situ hybridization (CISH) on 6 cases of XGET/KPGCT. All cases were positive with CSF1 CISH and showed increased expression of CSF1 by qPCR. Our findings provide additional evidence that the CSF1/CSF1R pathway is involved in the pathogenesis of XGET/KPGCT. These findings suggest a possible role for CSF1R inhibition in the treatment of unresectable or metastatic XGET/KPGCT.

MRI Prediction Model for Tenosynovial Giant Cell Tumor with Risk of Diffuse-type

RATIONALE AND OBJECTIVES

To propose a magnetic resonance imaging (MRI) prediction model for diffuse-type tenosynovial giant cell tumors (D-TSGCTs).

MATERIALS AND METHODS

Anatomic locations were classified and then nodularity, margin, peripheral and internal hypointensity, and bone and cartilage involvement were evaluated on MRI. Student's t-test, chi-square test, diagnostic performance, logistic regression analysis, and decision tree were performed.

RESULTS

Nineteen intra-articular (11 localized; eight diffuse) and 55 extra-articular (44 localized; 11 diffuse) TSGCTs were included. Extra-articular D-TSGCTs showed significantly more frequent multinodular (72.7% vs. 25.0%, p = 0.009), and infiltrative lesions (90.9% vs. 34.1%, p = 0.002), without peripheral hypointensity (90.9% vs. 18.2%, p < 0.001), and contained granular internal hypointensity (72.7% vs. 31.8%; p = 0.003) with more frequent bone (81.8% vs. 27.3%; p = 0.003) and cartilage (50.0% vs. 0.0%; p = 0.038) involvement than localized-type. Intra-articular D-TSGCT also showed significance in all MRI features (100.0% vs. 9.1%, p = 0.001; 100.0% vs. 27.3%, p = 0.007; 100.0% vs. 36.4%, p = 0.018; 100.0% vs. 27.3%, p = 0.007; 50.0% vs. 0.0%, p = 0.038), except bone involvement (37.5% vs. 9.1%, p = 0.352) than localized-type. Cartilage involvement revealed the highest specificity (88.6-100.0%), regardless of location. Nodularity (100.0%; odds-ratio [OR]: 70.000) and peripheral hypointensity (90.9%; OR: 62.250) demonstrated the highest sensitivities ORs for D-TSGCT in intra-articular and extra-articular cases, respectively. MRI models for D-TSGCG beginning with the cartilage involvement in both anatomic locations and next on nodularity and peripheral hypointensity in intra-articular and extra-articular locations, respectively, exhibited sensitivity and specificity of 100% and 90.9% for intra-articular and 100% and 77.2% for extra-articular TSGCTs, respectively.

CONCLUSION

MRI can suggest the risk of D-TSGCT by combining imaging features with anatomic locations.

Case report of a giant cell tumor of the carotid sheath

Giant cell tumor of the soft tissue (GCTST) is a neoplasm with low malignant potential and typically affects the trunk and extremities. Herein, we present a case of a palpable right neck mass diagnosed as a GCTST of the carotid sheath in a 38-year-old woman. A review of the imaging characteristics as well as of the differential diagnoses of primary neoplasms of the carotid space is presented.

Outcomes of Surgical Treatment for Localized Tenosynovial Giant-Cell Tumor of the Foot and Ankle: A Case Series

Background

Giant cell tumor of the tendon sheath (GCTTS), also termed Tenosynovial giant cell tumor (TGCT), is a locally aggressive tumor which originates from tendon sheaths or bursas. Around 3-5% of these tumors arise from foot and ankle. Localized lesions in this area are often manifested as firm masses or nodules with slow but continuous progression through months and years. Pain associated with weight-bearing, as well as limitations in joint motions, may be reported, depending on tumor's location. Surgery is the treatment of choice for the definitive removal of GCTTSs with the aim to eradicate the neoplasm and restore the lower limb's functionality.

Methods

Thirteen cases suffering from GCTTS of the foot and ankle underwent surgical resection at our institution between 2017 and 2022. For each case we recorded pre-operative and post-operative symptoms, as well as their pre-operative and post-operative functional status according to both MSTS and AOFAS scores. Eventual complications and local recurrences were reported.

Results

Each patient experienced an at least mild pain before surgical treatment. The mean pre-operative MSTS and AOFAS scores were 22.8 and 70.7, respectively. The mean tumor size was 17.7 mm. Each patient received a resection with wide margins. Two cases (15.4%) had local recurrences. None had major complications at their latest follow-up. After the surgery, the mean post-operative MSTS and AOFAS scores increased to 28.3 and 92.2, respectively.

Conclusion

Resection with wide margins for foot and ankle GCTTS is effective in restoring the patients' lower limb functionality and is associated with reasonable local recurrence rates.

Current therapies and future prospective for locally aggressive mesenchymal tumors

Locally aggressive mesenchymal tumors comprise a heterogeneous group of soft tissue and bone tumors with intermediate histology, incompletely understood biology, and highly variable natural history. Despite having a limited to absent ability to metastasize and excellent survival prognosis, locally aggressive mesenchymal tumors can be symptomatic, require prolonged and repeat treatments including surgery and chemotherapy, and can severely impact patients' quality of life. The management of locally aggressive tumors has evolved over the years with a focus on minimizing morbid treatments. Extensive oncologic surgeries and radiation are pillars of care for high grade sarcomas, however, play a more limited role in management of locally aggressive mesenchymal tumors, due to propensity for local recurrence despite resection, and the risk of transformation to a higher-grade entity following radiation. Patients should ideally be evaluated in specialized sarcoma centers that can coordinate complex multimodal decision-making, taking into consideration the individual patient's clinical presentation and history, as well as any available prognostic factors into customizing therapy. In this review, we aim to discuss the biology, clinical management, and future treatment frontiers for three representative locally aggressive mesenchymal tumors: desmoid-type fibromatosis (DF), tenosynovial giant cell tumor (TSGCT) and giant cell tumor of bone (GCTB). These entities challenge clinicians with their unpredictable behavior and responses to treatment, and still lack a well-defined standard of care despite recent progress with newly approved or promising experimental drugs.

Tenosynovial giant cell tumors of digits: MRI differentiation between localized types and diffuse types with pathology correlation

OBJECTIVE

To compare the MRI findings between the localized- and diffuse-type tenosynovial giant cell tumors (TSGCTs) of digits with pathology correlation.

METHODS

Twenty-eight patients with newly diagnosed TSGCTs of digits (22 localized and 6 diffuse types) who underwent preoperative MRI and surgical excision were included from Jan. 2015 to September 2021. MRI findings regarding nodularity, margins, morphology of hypointensity with pathology correlation, and disease extent (bone erosion, articular involvement, muscle involvement, tendon destruction, and neurovascular encasement) were assessed.

RESULTS

Diffuse type was significantly larger (P = 0.006), more multinodular on both MRI and pathology (P = 0.038, both) with significant agreement, and infiltrative on both MRI and pathology (P < 0.001, both) with substantial agreement, and showed central granular on MRI and strong hemosiderin deposition on pathology (P = 0.022 and P = 0.021) with moderate agreement than localized type. Localized type showed significantly more frequent peripheral capsules on both MRI and pathology (P < 0.001, both) with moderate agreement than diffuse type. However, the septum on both MRI and pathology showed no statistically significant difference between the two groups (P = 0.529 and P = 0.372) without significant agreement. The disease extent was more severe in the diffuse type than the localized type regarding articular involvement (P < 0.001), muscle involvement (P < 0.001), and tendon destruction (P = 0.010). No statistically significant differences were found between the two groups regarding bone erosion (P = 0.196) or neurovascular bundle encasement (P = 0.165).

CONCLUSIONS

Diffuse-type TSGCTs of digits presented as locally aggressive lesions with larger, multinodular, infiltrative masses exhibiting stronger hemosiderin deposition and more severe disease extents of articular, muscle, and tendon involvement than the localized type.

The Clinical Effect of Topical Application of Tranexamic Acid in Arthroscopic Synovectomy of Pigmented Villonodular Synovitis of the Knee

This study investigated the clinical effect of topical application of tranexamic acid (TXA) in arthroscopic synovectomy of pigmented villonodular synovitis (PVNS) of the knee. Eighty patients who were diagnosed with unilateral knee PVNS underwent arthroscopic synovectomies from January 2017 to January 2021 and were retrospectively investigated in this study. Patients were divided into two groups: group A was the control group, whereas patients in group B received an intra-articular injection of 50 mL of TXA (1 g:100 mL) immediately after the synovectomies. The primary outcome measurement was the drainage volume of the affected knee in each postoperative stage, as well as the hematological parameters. Secondary outcomes included visual analog scale score, knee range of motion, and Lysholm score. Postoperative complications were also recorded. A lower volume of drainage was found in group B than in group A on postoperative day (POD) 1, on POD 2, and in total (POD 1, P=.000; POD 2, P=.000; total, P=.000). A lower visual analog scale pain score in group B was noticed on POD 1 (P=.000) and POD 2 (P=.005). Range of motion (P=.019) and Lysholm score (P=.001) were significantly superior in group B compared with group A on POD 14. Regarding complications, 3 patients in group A and 1 patient in group B developed deep venous thrombosis after surgery. Hematomas were found intra-articularly in 5 patients in group A during follow-up. Intraarticular topical application of TXA was effective in reducing postoperative bleeding and early postoperative pain for patients who underwent arthroscopic synovectomy of PVNS. [Orthopedics. 20XX;XX(X):xx-xx.].

Surgical treatment of spinal tenosynovial giant cell tumor: Experience from a single center and literature review

Introduction

Spinal tenosynovial giant cell tumor (TGCT) is a rare benign primary spinal tumor with aggressive behavior. The treatment strategy and prognosis of spinal TGCT remain unclear. This retrospective study aimed to evaluate the effectiveness of surgical treatment of spinal TGCT.

Methods

We enrolled 18 patients with spinal TGCT who underwent surgical treatment in our hospital between January 2002 and January 2021. Additionally, we reviewed 72 cases of spinal TGCT with surgical treatment reported in the previous literature. Therefore, a total of 90 cases of spinal TGCT were evaluated for their clinical characteristics, surgical details, radiotherapy, and prognosis.

Results

In terms of the extent of resection, 73 cases (81.1%) underwent gross total resection (GTR), and 17 cases (18.9%) underwent subtotal resection (STR). Regarding the technique of GTR, 12 cases (16.7%) underwent en bloc resection, while 60 cases (83.3%) underwent piecemeal resection. During a median follow-up duration of 36 months (range: 3-528 months), 17.8% (16/90) cases experienced local recurrence/progression. The local recurrence/progression rate in cases that underwent GTR was 8.2% (6/73), which was significantly lower than that in cases with STR (58.8%, 10/17) (p<0.001). The local recurrence/progression rate of en bloc resection was 8.3% (1/12), and that of piecemeal resection was 8.3% (5/60). Twelve cases underwent perioperative adjuvant radiotherapy, and one (8.3%, 1/12) of them showed disease progression during follow-up. Six recurrent/progressive lesions were given radiotherapy and all of them remained stable in the subsequent follow-up. Eight recurrent/progressive lesions were only treated with re-operation without radiotherapy, and half of them (50.0%, 4/8) demonstrated repeated recurrence/progression in the subsequent follow-up.

Conclusion

Surgical treatment could be effective for spinal TGCT cases, and GTR is the preferred surgical strategy. Piecemeal resection may be appropriate for spinal TGCT cases with an acceptable local recurrence/progression rate. Perioperative adjuvant radiotherapy may reduce the risk of postoperative local recurrence/progression, and radiotherapy plays an important role in the treatment of recurrent/unresectable spinal TGCT lesions.

Best clinical management of tenosynovial giant cell tumour (TGCT): A consensus paper from the community of experts

Tenosynovial giant cell tumour (TGCT) is a rare, locally aggressive, mesenchymal tumor arising from the joints, bursa and tendon sheaths. TGCT comprises a nodular- and a diffuse-type, with the former exhibiting mostly indolent course and the latter a locally aggressive behavior. Although usually not life-threatening, TGCT may cause chronic pain and adversely impact function and quality of life (QoL). CSFR1 inhibitors are effective with benefit on symptoms and QoL but are not available in most countries. The degree of uncertainty in selecting the most appropriate therapy and the lack of guidelines on the clinical management of TGCT make the adoption of new treatments inconsistent across the world, with suboptimal outcomes for patients. A global consensus meeting was organized in June 2022, involving experts from several disciplines and patient representatives from SPAGN to define the best evidence-based practice for the optimal approach to TGCT and generate the recommendations presented herein.

Complementary Effects of Surgery and Pexidartinib in the Management of Patients with Complex Diffuse-Tenosynovial Giant Cell Tumor

Tenosynovial giant cell tumor (TGCT) is a rare neoplasm of the joint synovium that has a wide clinical spectrum including pain and stiffness in the affected joint, joint swelling, periarticular erosions, and cartilage loss, which can severely impact quality of life. The mainstay treatment for TGCT has been surgery involving partial or total synovectomy using arthroscopic or open techniques. However, surgical resection alone is associated with high recurrence rates, particularly in diffuse-TGCT (D-TGCT) cases. The 3 cases presented here summarize a combination approach (surgery+pexidartinib [tyrosine kinase inhibitor]) in patients with previously unresectable or inoperable D-TGCT. Case 1-Hip. A 29-year-old male was treated with pexidartinib prior to surgery, resulting in tumor reduction. A left total hip arthroplasty (THA) was then performed with a lack of recurrence in 12 months postoperative, and the patient currently on pexidartinib treatment. Case 2-Foot. A 35-year-old female, nearly a decade following a left foot mass resection, was treated with pexidartinib following disease recurrence. A decrease in soft tissue lesions at the midfoot and decreased marrow enhancement at the first metatarsal head were seen within 4-5 months of pexidartinib treatment; the patient is currently on pexidartinib (400 mg/day) with improved symptom control. Case 3-Knee. A 55-year-old male patient received pexidartinib pre- and postoperatively. A reduction in swelling and the size of the popliteal cyst was significant and maintained, with the synovial disease growing when pexidartinib was discontinued. Surgery and adjuvant therapy eliminated the disease as of the last follow-up visit (11 months postoperative). These cases provide a unique perspective based on tumor location, type/timing of treatment strategy, and patient outcomes. Optimal treatment strategies for this debilitating disease may entail utilizing a combination approach (surgery+systemic treatment) to reduce surgical morbidity and the risk of postoperative disease recurrence.

Giant cell tumor of the tendon sheath of the toe: case report of an unusual localization

INTRODUCTION AND IMPORTANCE

The purpose of this study is to highlight a rare entity of unusual location and to report our therapeutic attitude in this regard, while detailing the diagnostic criteria and therapeutic management.

CASE PRESENTATION

We describe the case of a 32 years old woman with a swelling of the big toe initially neglected by the patient, the evolution is marked by a discomfort when wearing shoes, it was a firm mass of 2 cm slightly painful without local inflammatory signs with bone lysis on radiography, The MRI showed an invasion of the flexor and extensor tendons of the hallux, our approach was a carcinological tumor exeresis and arthrodesis while preserving the toe since the pedicle was not invaded, the histological examination confirmed the diagnosis and the evolution is good without tumor recurrence.

CLINICAL DISCUSSION

A giant cell tumor of the tendon sheaths (GCTTC) usually presents as a firm slow growing mass, the radiological assessment shows bone erosions, an MRI for extension assessment and histological confirmation are mandatory, malignant degenerations are unusual but should always be investigated, treatment is based on the most complete surgical resection to avoid the risk of recurrence, adjuvant radiotherapy can be done in case of incomplete resection but it is a controversial subject.

CONCLUSION

GCTTC are benign tumors that may be locally malignant because of the invasion of noble structures, which makes their complete exeresis difficult. The diagnosis is based on clinical and radiological criteria and requires histological confirmation.

PD-L1 Status in Tenosynovial Giant Cell Tumors

Background and Objectives: Tenosynovial giant cell tumors (TSGCTs) are benign soft tissue tumors that are divided into localized- and diffuse-type tumors, according to the World Health Organization classification of soft tissue tumours. The diffuse-type TSGCT sometimes behave aggressively and poses treatment challenges especially in patients with neurovascular involvement. Symptomatic patients who are not good candidates for surgery due to high morbidity risk may benefit from medical therapy. Objectives: Drugs that target programmed death ligand 1 (PD-L1) are among a new generation of medical therapy options, which, recently, have been explored and have displayed promising results in various cancer types; therefore, we aimed to investigate the PD-L1 status of TSGCTs as a possible therapeutic target. Materials and Methods: We assessed the PD-L1 status of 20 patients (15 men and 5 women, median age = 39 years) that had been diagnosed with TSGCTs in a single institution, between 2018 and 2020. The patients had localized- (n = 7) and diffuse-type (n = 13) TSGCTs. Formalin-fixed paraffin-embedded (FFPE) blocks were retrospectively retrieved from the pathology department. An immunohistochemical analysis was performed in sections of 3 micron thickness from these blocks. Results: Seventy-five percent of our patients with TSGCTs were immunopositive to PD-L1 staining. Conclusions: Taking into consideration the high positivity rate of PD-L1 staining in TSGCTs, PD-L1 blockage may be used as a valuable medical treatment for TSGCTs; however, further studies are needed.

Case Report: Giant Cell Tumor of Tendon Sheath After Breast Augmentation

Giant cell tumor of tendon sheath (GCTTS) is a benign tumor. It occurs predominantly in the hands, ankles, and knees. A 39-year-old female presented with GCTTS in the right breast after breast augmentation. There was a clear borderline between the tumor and breast tissue. In terms of morphological appearance, synovial metaplasia could be observed in part of the collagenous capsule. The tumor was moderately cellular and was composed of synovium-like monocytes. The main part of the tumor was blended with nested and scattered xanthomatous cells, lymphocytes, and osteoclast-like giant cells. Hemosiderin granules were distributed in the lesion. Immunohistochemical staining and fluorescence in situ hybridization (FISH) analyses were performed. CD68 staining was positive in osteoclast-like giant cells. In addition, neither significant USP6 translocation nor CSF1 translocation was detected by FISH. We hypothesized that the pathogenesis of this rare GCT-TS was based on synovial metaplasia and did not depend on the translocation of classical CSF1.

Surgical Treatment of Sacroiliac Pigment Villous Nodular Synovitis: A Case Report and Literature Review

Pigmented villonodular synovitis (PNVS) is a rare and disabling disease that is thought to occur mostly in the knee joint. Here, the authors first present a unique case of PNVS occurring at the sacroiliac joint. The patient complained of sacroiliac joint pain with mild swelling. CT and MRI showed that the tumor was ~63 by 91 by 107 mm in size, and was considered to be a fibrous borderline or low-grade malignancy. Intraoperative macroscopic features of the synovitis during operation suggested PNVS, which was confirmed by histopathological examination. The clinical symptoms and signs of the disease, in this case, are not obvious, and radiological investigations, including MRI, suggest high aggressiveness. The author believes that it may be more likely to relapse and metastasis and recommends complete removal of the synovial membrane and regular follow-up, while preoperative or postoperative radiotherapy and molecular targeted therapy are not recommended for the time being.

Tenosynovial giant cell tumors (TGCT): molecular biology, drug targets and non-surgical pharmacological approaches

INTRODUCTION

Tenosynovial giant cell tumor (TGCT) is a mono-articular, benign or locally aggressive and often debilitating neoplasm. Systemic therapies are becoming part of the multimodal armamentarium when surgery alone will not confer improvements. Since TGCT is characterized by colony-stimulating factor-1 (CSF1) rearrangements, the most studied molecular pathway is the CSF1 and CSF1 receptor (CSF1R) axis. Inhibiting CSF1-CSF1R interaction often yields considerable radiological and clinical responses; however, adverse events may cause treatment discontinuation because of an unfavorable risk-benefit ratio in benign disease. Only Pexidartinib is approved by the US FDA; however, the European Medicines Agency has not approved it due to uncertainties on the risk-benefit ratio. Thus, there is a need for safer and effective therapies.

AREAS COVERED

Light is shed on disease mechanisms and potential drug targets. The safety and efficacy of different systemic therapies are evaluated.

EXPERT OPINION

The CSF1-CSF1R axis is the principal drug target; however, the effect of CSF1R inhibition on angiogenesis and the role of macrophages, which are essential in the postoperative course, needs further elucidation. Systemic therapies have a promising role in treating mainly diffuse-type, TGCT patients who are not expected to clinically improve from surgery. Future drug development should focus on targeting neoplastic TGCT cells.

Intra-Articular Tumors

The intra-articular space is a relatively rare site of occurrence of neoplastic diseases. The 2 distinct groups of clinicopathologic entities that exhibit an almost exclusive tropism for the joints are represented by synovial chondromatosis and tenosynovial giant cell tumors (TGCT). Synovial chondromatosis is a locally aggressive chondrogenic neoplasm that very rarely can show malignant behavior. TGCT occur in 2 main variants, the localized variant and the more locally aggressive diffuse type. Malignant TCGT is exceedingly rare and is characterized by significant rates of both local recurrence and metastatic spread.

Grading System and Surgical Strategy for Temporal Bone Diffuse-Type Tenosynovial Giant Cell Tumor

OBJECTIVES

To develop a novel grading system and appropriate surgical approaches for patients with diffuse type tensosynovial giant cell tumor (D-TGCT) of the temporal bone.

STUDY DESIGN

Retrospective cohort study.

METHODS

We retrospectively reviewed 31 patients with temporal bone D-TGCT between June 2012 and July 2021. All patients underwent comprehensive clinical evaluations, including clinical presentations, hearing threshold, imaging studies, surgical approaches, and prognosis. A grading system was developed based on the tumor location and adjacent neurovascular structures involvement according to imaging and intraoperative findings.

RESULTS

In this study, grade II tumors were the most common (13/31), followed by grades I (7/31), III (7/31), and IV (4/31) tumors. Seven grade I patients received the subtemporal middle cranial fossa approach (SMCF) combined with the canal wall up mastoidectomy and tympanoplasty (CWUT). Nine grade II patients underwent SMCF combined with subtotal petrosectomy (SPTR), and four grade II patients underwent SMCF combined with CWUT. Seven grade III patients received SMCF combined with SPTR and dura mater reconstruction, and four grade IV patients underwent infratemporal fossa approach type B. Gross total resection was achieved in all patients, and the median follow-up time was 30.1 months (range, 4-96 months). Three patients (one grade II, one grade III, and one grade IV) had recurrence during follow-up, and the patient with grade III tumor had two recurrences.

CONCLUSIONS

Gross total resection is the first-line treatment for patients with D-TGCT of the temporal bone. This novel grading system enables surgeons to select optimal surgical strategy. Long-term follow-up is mandatory postoperatively.

LEVEL OF EVIDENCE

4 Laryngoscope, 2021.

Intramuscular Tenosynovial Giant Cell Tumor Harboring a Novel CSF1-CD96 Fusion Transcript

Tenosynovial giant cell tumors typically arise in the synovium of joints, bursae, or tendon sheaths. They may occur in an intra- or extra-articular location and can be divided into localized and diffuse types. The neoplastic nature of the lesion has been supported by a recurrent CSF1 gene rearrangement in a small subset of lesional cells, of which the most common fusion partner is COL6A3. Herein, we report a case of intramuscular localized tenosynovial giant cell tumor harboring a novel CSF1-CD96 fusion transcript, thus expanding the molecular profile of this tumor.

Pigmented Villonodular Synovitis Around the Elbow Joint That Required Upper Arm Amputation

Pigmented villonodular synovitis (PVNS) is a relatively rare benign proliferative disorder of the synovium, and it commonly occurs in the knee joint. A unique case of huge PVNS originating around the elbow joint that required upper arm amputation is reported. A 74-year-old woman had a 5-month history of right elbow pain and noticed a mass measuring 8 × 5 cm on the olecranon side. She had a past history of undergoing tumor resection and flap surgery 9 years earlier, diagnosed as a giant cell tumor involving the right elbow region. She had chronic renal failure, with a shunt on the right forearm. On magnetic resonance imaging, the tumor around the elbow joint showed low signal intensity on T1-weighted images and low to high intensity on T2-weighted images. It was thought that it was difficult to preserve the limb because of the size of the tumor and the shunt blood vessel. Therefore, upper arm amputation was performed. The histological diagnosis was PVNS. There was no recurrence of PVNS postoperatively. In the treatment of PVNS, initial surgery with complete resection of the synovial membrane and careful postoperative follow-up are considered important.

Limited usefulness of classic MR findings in the diagnosis of tenosynovial giant cell tumor

OBJECTIVE

To determine the frequency with which MRI of tenosynovial giant cell tumor demonstrates hemosiderin, visible intralesional fat signal, and proximity to synovial tissue.

MATERIAL AND METHODS

This is a retrospective study of 31 cases of tenosynovial giant cell tumors which had concomitant MRI. Images were examined for lesion size, morphology, origin, bone erosions, MRI signal characteristics, contrast enhancement, and blooming artifact, comparing prospective and retrospective reports. Histology was reviewed for the presence of hemosiderin and xanthoma cells.

RESULTS

Eight lesions were diffuse and 23 were localized nodules. Three lesions were located in subcutaneous tissue and 4 adjacent to tendons beyond the extent of their tendon sheath. All lesions exhibited areas of low T1- and T2-weighted signal. Blooming artifact on gradient echo imaging was present in 86% of diffuse and only 27% of nodular disease. There was interobserver variability of 40% in assessing blooming. Iron was visible on H&E or iron stain in 97% of cases. Fat signal intensity was seen in only 3% of cases, although xanthoma cells were present on in 48%. The correct diagnosis was included in the prospective radiology differential diagnosis in 86% of diffuse cases and 62% of nodular cases.

CONCLUSION

Blooming on GRE MRI has low sensitivity for nodular tenosynovial giant cell tumors and is not universal in diffuse tumors. There was high interobserver variability in assessment of blooming. Intralesional fat signal is not a useful sign and may occur adjacent to tendons which lack a tendon sheath and may occur in a subcutaneous location.

Bilateral Mirror-Symmetrical Giant Cell Tumor of the Tendon Sheath in the Foot and Ankle: A Case Report

Giant cell tumor of the tendon sheath is a slowly growing benign tumor. It usually arises from the tendon sheath and periarticular soft tissue of small joints. However, it may infrequently involve the large joints emerging around the knee, elbow, and hip joints. Giant cell tumor of the tibialis tendon sheath is rarely reported in the foot and ankle joint. Here, we report the first case in the medical literature of bilateral mirror-symmetrical giant cell tumor of the tendon sheath in the foot and ankle. A 12-year-old male presented with a bilateral and mirror-image mass on his ankles extending to the foot. It was painless but affected his gait and footwear. Staged complete resection was done first on the right then on the left side, with no recurrence after 1 year. The role of genes can be argued for this presentation and giant cell tumor's etiology, owing to the bilateralism and mirror-image presentation. Studies are needed to explore this genetic aspect and its role in management.

RNAscope CSF1 chromogenic in situ hybridization: a potentially useful tool in the differential diagnosis of tenosynovial giant cell tumors

Colony stimulating factor-1 (CSF1) upregulation and CSF1/colony-stimulating factor 1 receptor (CSF1R) signaling pathway is central to the tumorigenesis of tenosynovial giant cell tumors (TGCT) of both localized (LTGCT) and diffuse (DTGCT) types, and has been demonstrated in a small number of malignant tumors (MTGCT) as well. In situ hybridization for CSF1 mRNA has been shown to be potentially useful in the diagnosis of TGCT, although only a relatively small number of cases have been studied. We studied CSF1 mRNA expression using RNAscope chromogenic in situ hybridization (CISH) in standard tissue sections from 31 TGCT and 26 non-TGCT, and in tumor microarray slides (Pantomics normal MN0341, Pantomics tumor MTU391, Pantomics melanoma MEL961). Among normal tissues, CSF1 mRNA expression was invariably present in synovium (10/10, 100%) and absent in all other normal tissues. All LTGCT and DTGCT were positive (24/24, 100%), exclusively in large, eosinophilic synoviocytes. MTGCT contained large clusters of CSF1-positive malignant synoviocytes (8/8, 100%); malignant spindled cells were also positive. Among non-TGCT, CSF1 CISH was less often positive with high specificity (90%). CSF1-positive cases included leiomyosarcoma, giant cell tumor of bone and of soft parts, pulmonary carcinoma and others. The sensitivity and specificity of RNAscope CSF1 mRNA CISH for the diagnosis of TGCT were 100% and 90%, respectively. We conclude that RNAscope CSF1 CISH may be a valuable adjunct for the diagnosis of TGCT of all types, especially those with atypical or malignant morphologic features. Detection of CSF1 mRNA expression may also have predictive significance in cases where use of the CSF1 inhibitor pexidartinib is considered.

Postoperative radiotherapy for pigmented villonodular synovitis (PVNS): case series and literature review

Purpose:

Pigmented villonodular synovitis (PVNS) is a rare benign proliferative disease of the synovium with locally aggressive behaviour. We reviewed our experience using external beam radiotherapy (RT) in the treatment of PVNS.

Method:

We report five cases of PVNS who underwent Arthroscopic Synovectomy followed by postoperative RT in National Oncology centre in Oman. The total dose RT ranges between 30 and 36 Gray (Gy) Three-dimensional radiotherapy technique.

Conclusion:

Postoperative RT is effective in preventing disease recurrence and should be offered following maximal cytoreduction to enhance local control in PVNS.

The diffuse-type tenosynovial giant cell tumor (dt-TGCT) patient journey: a prospective multicenter study

Background

Tenosynovial giant cell tumor (TGCT) is a rare, locally aggressive neoplasm arising from the synovium of joints, bursae, and tendon sheaths affecting small and large joints. It represents a wide spectrum ranging from minimally symptomatic to massively debilitating. Most findings to date are mainly from small, retrospective case series, and thus the morbidity and actual impact of this rare disease remain to be elucidated. This study prospectively explores the management of TGCT in tertiary sarcoma centers.

Methods

The TGCT Observational Platform Project registry was a multinational, multicenter, prospective observational study involving 12 tertiary sarcoma centers in 7 European countries, and 2 US sites. This study enrolled for 2 years all consecutive ≥ 18 years old patients, with histologically diagnosed primary or recurrent cases of diffuse-type TGCT. Patient demographic and clinical characteristics were collected at baseline and every 6 months for 24 months. Quality of life questionnaires (PROMIS-PF and EQ-5D) were also administered at the same time-points. Here we report baseline patient characteristics.

Results

166 patients were enrolled between November 2016 and March 2019. Baseline characteristics were: mean age 44 years (mean age at disease onset: 39 years), 139/166 (83.7%) had prior treatment, 71/166 patients (42.8%) had ≥ 1 recurrence after treatment of their primary tumor, 76/136 (55.9%) visited a medical specialist ≥ 5 times, 66/116 (56.9%) missed work in the 24 months prior to baseline, and 17/166 (11.6%) changed employment status or retired prematurely due to disease burden. Prior treatment consisted of surgery (i.e., arthroscopic, open synovectomy) (128/166; 77.1%) and systemic treatments (52/166; 31.3%) with imatinib (19/52; 36.5%) or pexidartinib (27/52; 51.9%). Treatment strategies at baseline visits consisted mainly of watchful waiting (81/166; 48.8%), surgery (41/166; 24.7%), or targeted systemic therapy (37/166; 22.3%). Patients indicated for treatment reported more impairment compared to patients indicated for watchful waiting: worst stiffness NRS 5.16/3.44, worst pain NRS 6.13/5.03, PROMIS-PF 39.48/43.85, and EQ-5D VAS 66.54/71.85.

Conclusion

This study confirms that diffuse-type TGCT can highly impact quality of life. A prospective observational registry in rare disease is feasible and can be a tool to collect curated-population reflective data in orphan diseases.

Name of registry: Tenosynovial Giant Cell Tumors (TGCT) Observational Platform Project (TOPP).

Trial registration number: NCT02948088.

Date of registration: 10 October 2016.

URL of Trial registry record: https://clinicaltrials.gov/ct2/show/NCT02948088?term=NCT02948088&draw=2.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13023-021-01820-6.

Tenosynovial giant cell tumor of the distal tibiofibular joint

Tenosynovial giant cell tumors are extremely rare tumors with highly nonspecific symptoms. This benign but aggressive disease has a slow course of progression; however, it can ultimately lead to irreversible damage to a joint. Here we describe a case of a 45-year-old female with a diagnosis of tenosynovial giant cell tumors of the distal tibiofibular joint, the second case described in the literature for such location. Appropriate imaging studies and ultimately histologic studies are necessary for the correct diagnosis. Some locations are particularly unusual for these tumors making a high level of suspicion as well as treatment by an oncology orthopedic surgery specialist at a high-volume center paramount.

Magnetic resonance imaging features of intra-articular tenosynovial giant cell tumor in children

BACKGROUND

Magnetic resonance imaging (MRI) plays a critical role in disease characterization of intra-articular tenosynovial giant cell tumor.

OBJECTIVE

To characterize the MRI features of intra-articular tenosynovial giant cell tumor in children with respect to disease subtype and anatomical location.

MATERIALS AND METHODS

This retrospective study included children with tenosynovial giant cell tumor who underwent preoperative MRI between January 2006 and May 2020. Two radiologists reviewed each examination to determine disease subtype, signal intensities and the presence of an effusion, osseous changes, chondromalacia, juxtacapsular disease and concomitant joint involvement. Fisher exact, Mann-Whitney U, and Kruskal-Wallis H tests were used to compare findings between subtypes and locations.

RESULTS

Twenty-four children (16 girls, 8 boys; mean age: 13.1±3.8 years) with 19 knee and 5 ankle-hindfoot tenosynovial giant cell tumor had either diffuse (n=15) or localized (n=9) disease. An effusion (P=0.004) was significantly more common with diffuse than localized disease. There was no significant difference in MRI signal (P-range: 0.09-1) or other imaging findings (P-range: 0.12-0.67) between subtypes. Children with knee involvement were significantly more likely to present with diffuse disease while those with ankle-hindfoot involvement all presented with focal disease (P=0.004). Juxtacapsular (n=4) and concomitant proximal tibiofibular joint involvement (n=5) were observed with diffuse disease in the knee. Erosions (P=0.01) were significantly more common in the ankle than in the knee.

CONCLUSION

In our study, diffuse tenosynovial giant cell tumor was more common than localized disease, particularly in the knee where juxtacapsular and concomitant proximal tibiofibular joint disease can occur.

Case Report: Extra-Articular Diffuse Tenosynovial Giant Cell Tumor of the Temporomandibular Joint

Diffuse tenosynovial giant cell tumor (D-TSGCT) is a benign but locally destructive tumor of synovium that may involve joints, tendon sheaths, and bursae. Its occurrence in the temporomandibular joint (TMJ) is extremely rare. The authors reported a case of 48-year-old man with an extra-articular D-TSGCT in the TMJ with medial cranial fossa extension. computed tomography (CT) and magnetic resonance imaging (MRI) features are described. The lesion was a cystic-solid mass centered at the temporal bone without involvement of the condylar head, and its solid component presented high-density on CT and hypointensity on MRI. No signs of recurrence or metastasis was observed during 12-months of follow-up. The present report suggested the potential characteristics of radiologic imaging of D-TSGCT in TMJ.

Diffuse-Type Giant Cell Tumor of the Paratenon of Achilles Tendon Requiring Reconstruction Using Bilateral Autografts: A Case Report

Although a diffuse-type giant cell tumor is a rare benign lesion, when it develops it tends to localize to the tendons of the hand and foot. In this study, we report the case of a 41-year-old male patient who was diagnosed with diffuse-type paratenon giant cell tumor involving the Achilles tendon. The duration of the bilateral tumors was 8 years. He visited first affiliated Hospital of Wenzhou Medical University for medical attention. Both his Achilles tendons required removal. The reconstructed Achilles tendon was replaced using tissue derived from the knee and foot. Postoperatively, the patient recovered well and regained full range of motion in the ankle. The use of autografts may shorten patients' recovery period.

Tenosynovial Giant Cell Tumor in an Infant

In this report, the authors describe a child presenting at 6 months old with a rapidly expanding extracranial left temporal mass concerning for malignancy. The mass was successfully treated at 16 months with radical surgical excision. The patient was found to have a tenosynovial giant cell tumor, diffuse type, completely encased by the temporalis muscle. To our knowledge, this is the first report of a case of diffuse type tenosynovial giant cell tumor in the temporalis muscle, without articular involvement, presenting in an infant.

Cytomorphological Evaluation of Synovial Lesions in a Tertiary Care Centre in North India: A Retrospective Study

Background:

Numerous pathological processes involve synovium and periarticular tissues that are characteristic and in some cases specific to a particular disease. Synovial fluid is a thick, stringy fluid found in the cavity of synovial joint. Examination of the synovium plays a key role in the diagnosis of many joint diseases.

Aims:

The aim of this study was to study the spectrum of synovial lesions on fine needle aspiration cytology (FNAC) and to compare the cytological diagnosis with histopathological findings.

Material and Methods:

This retrospective diagnostic analytical study was carried out in the Department of Pathology. Sixty-six patients with suspected synovial lesions referred from other departments who underwent FNAC during 1 year from January 2017 to December 2017 were included in the study. The slides along with records of the patients were retrieved and findings recorded. Histopathological evaluation was performed wherever possible and compared with cytological diagnosis.

Results:

Non-neoplastic lesions accounted for 80.3% cases followed by benign tumors (15.2%). Ganglion cyst was the commonest non-neoplastic lesion (60.6%, 40/66), while tenosynovial giant cell tumor was the commonest neoplasm (12.1%, 8/66) observed in our study. Solitary case of synovial sarcoma was also observed. Histopathological evaluation was performed in 14 cases and FNAC had overall diagnostic accuracy of 85.7% in diagnosis of these lesions.

Conclusions:

FNAC is a useful tool with high diagnostic accuracy in the evaluation of synovial lesions.

Multiple systemic treatment options in a patient with malignant tenosynovial giant cell tumour

Tenosynovial giant cell tumour (TGCT) is a group of rare soft tissues neoplasia affecting synovial joints, bursae and tendon sheaths and is classified as localized type or diffuse type. The diffuse type (TGCT-D), also known as ‘pigmented villonodular (teno)synovitis’ is characterized by local aggressivity, with invasion and destruction of adjacent soft-tissue structures, and high local recurrence rate. Radical surgery remains the standard therapy while adjuvant radiotherapy may help to control local spread. Malignant TGCT is characterized by high rate of local recurrences and distant metastasis. Few cases of malignant TGCT and very few evidences on systemic therapies are described in the literature, so, to date, no systemic treatment is approved for this rare disease. We report the case of a malignant TGCT patient treated with many different systemic therapies, including chemotherapy and tyrosine-kinase inhibitors, and performed a review of the literature on the systemic treatment options of this rare tumour.

Tenosynovial giant cell tumor in the foot and ankle

BACKGROUND

Tenosynovial giant cell tumor (TSGCT) originates from the synovial cells of the tendon sheath and is the most common soft tissue tumor of the foot and ankle. Due to the lack of clinical data about TSGCT in the foot and ankle, this study was performed with the aim of investigating the clinical characteristics, and surgical outcomes that might predict the likelihood of recurrence.

METHODS

Clinical data, obtained from the pathology records and the clinic files, along with the tumor subtype, local recurrence, and patient functional status among 26 cases of TSGCT were evaluated with the mean 73 months follow-up period.

RESULTS

There were 26 patients including 16 males and 10 females with a mean age of 40 years, who underwent surgery. There were 15 localised TSGCT and 11 diffuse TSGCT. The diffuse TSGCT was more likely to be in the hindfoot dorsum (54,5%, 6/11). The localised TSGCT was mostly located in the forefoot (80%, 12/15). The recurrence rate in the diffuse TSGCT was 27,3% (3/11). In the localised TSGCT, recurrence was seen in 6,6% of patients (1/15). The mean AOFAS score was 79.

CONCLUSION

Diffuse TSGCT is more likely to occur in the hindfoot and localised TSGCT is more common in the forefoot. Excision with clear margins is an effective treatment for TSGCT, with good oncological and clinical outcomes. But the orthopaedic surgeons should consider the equilibrium between surgical margins and the functional status of the patient.

Clinical and immunohistochemical analysis of diffuse tenosynovial giant cell tumour of the temporomandibular joint

The objective of this study was to summarize diagnostic points and treatment strategies for diffuse tenosynovial giant cell tumours (D-TSGCTs) of the temporomandibular joint (TMJ), and to evaluate the expression of proteins related to bone destruction and recurrence. The clinical and histopathological characteristics of 24 cases were analysed retrospectively. TRAP staining and immunohistochemical staining for MMP-9, MMP-13, and Ki-67 were performed. The median age of the patients was 45.5 years; the female to male ratio was 1.7:1. In 11 cases (45.8%), skull base destruction seen on computed tomography was confirmed by surgery. Computer-assisted navigation was performed in six cases. Four patients received adjuvant radiotherapy after first surgery. Five patients had recurrent lesions. Multinucleated giant cells were positive for TRAP, MMP-9, and MMP-13. The average Ki-67 index of the recurrent cases was significantly higher than that of the non-recurrent ones (P<0.05). This study demonstrates the aggressive and recurrent nature of D-TSGCT occurring in the TMJ. Computer-assisted navigation is helpful to protect vital structures and determine margins. Adjuvant postoperative radiotherapy is recommended for local control of residual or recurrent tumour. In conclusion, MMP-9 and MMP-13 may play a role in bone destruction of D-TSGCT, and the Ki-67 index has predictive significance for recurrence.

Risk factors for early osteoarthritis in tenosynovial giant cell tumour

OBJECTIVE

Tenosynovial giant cell tumour (TGCT) is locally aggressive entity affecting young people (around 4^th decade of life) and can cause joint destruction. It could be nodular or diffuse. These two varieties are histological and genetically similar, but present a different prognosis. The aim of this study is to identify risk factors for local recurrence and predisposing factors for the development of early osteoarthritis in patients with TGCT.

MATERIAL AND METHODS

We conducted a retrospective study of 35 patients with an anatomopathological diagnosis of TGCT in our Institution from 1991 to 2017. The mean follow-up was 8.2 years. Demographic variables, characteristics of the primary tumor and its evolution were collected to assess the risk factors for local recurrence and early osteoarthritis.

RESULTS

The diffuse type was identified as a risk factor for the development of osteoarthritis (p=0.01) and for local recurrence (p=0.015). Osteoarthritis was more frequent in the hip and ankle than in the knee (p=0.03). A difference of 16 months in the duration of symptoms prior to diagnosis between those who developed osteoarthritis and those who did not was observed (p=0.05).

CONCLUSIONS

The diffuse type is more aggressive than the nodular type; it is associated with a higher risk of osteoarthritis and local recurrence. The hip and ankle present a higher risk of osteoarthritis than other joints. The time of evolution of the symptoms before diagnosis and adequate treatment, negatively influences the development of osteoarthritis.

Molecular Profiling of Atypical Tenosynovial Giant Cell Tumors Reveals Novel Non-CSF1 Fusions

Tenosynovial giant cell tumor (TGCT) is a benign neoplasm characterized by recurrent fusions involving the colony-stimulating factor 1 (CSF1) gene and translocation partners including collagen type VI alpha 3 chain (COL6A3) or S100 calcium-binding protein A10 (S100A10). Herein, we report three atypical TGCT cases with very unusual morphology comprising areas with increased cellular atypia, mitotic activity, and worrisome features that harbor unique non-CSF1 gene fusions. Anchored multiplex PCR (AMP) for next-generation sequencing utilizing a customized panel targeting 86 cancer-related genes was performed, and it identified novel non-CSF1-driven gene fusions: NIPBL-ERG, FN1-ROS1, and YAP1-MAML2. Screening of three control TGCTs with conventional morphology found translocations involving CSF1, with partner genes COL6A3, FN1, and newly identified KCNMA1. All novel fusions were further validated by reverse transcriptase-PCR (RT-PCR) and Sanger sequencing. Late and multiple local recurrences occurred in the atypical TGCTs, while no recurrences were reported in the conventional TGCTs. Our findings reveal that atypical TGCTs harbor gene fusions not implicating CSF1 and suggest that non-CSF1 fusions potentially confer greater propensity to recurrences and local aggressiveness while indicating the presence of alternate pathogenic mechanisms that warrant further investigation.

KRAS mutant tenosynovial giant cell tumor in a pediatric patient: a case report

Tenosynovial giant cell tumors (TSGCT) are a group of rare, benign soft tissue tumors with common histologic and cytogenetic features, with a median age of diagnosis being 47 years. Generally divided into localized and diffuse subtypes, TSGCTs are typically driven by overexpression of macrophage colony stimulating factor receptor-1 (CSF1R). Treatment of TSGCT is tumor resection, followed by radiation therapy in cases of incomplete resection. Even when the tumor is completely removed, recurrence rates can be as high as 30% in some anatomical locations. Here we report the identification of a previously undescribed KRAS p.G12D activating mutation within a pediatric TSGCT patient, who clinically presented with an enlarging right lower extremity mass pathologically consistent with TSGCT. The patient continues to be in remission three years after complete surgical removal. KRAS mutations are usually found in adult cancers, such as lung and pancreatic, as well as giant cell lesion of the jaw. This case demonstrates the utility of integrative clinical sequencing in identifying lesions with aggressive potential and aiding in complex diagnoses.

Risk Factors Associated With Postoperative Recurrence in Patients With Tenosynovial Giant Cell Tumor of the Hand: A Retrospective Cohort Study

Identification of risk factors for recurrence of tenosynovial giant cell tumors of the hand is crucial to provide adequate preoperative counseling and tailor surgical treatment. However, the risk factors are still controversial, which are the subject of this research.Recently, we conducted a retrospective cohort study of 135 consecutive patients with giant cell tumors of the tendon sheath of the hand from January 2010 to July 2016. All patients underwent surgical excision, received necessary imaging examinations, and had routine follow-up and thus were identified as those who had recurrence by confirmation of reoperation, and the duration ranged from 24 to 103 months (mean, 53.5 ± 21.4 months). There were 14 local recurrences (10.4%) within 6 to 24 months, respectively, after surgery. Data pertaining to sex, age, tumor sites, tumor size, tumor number, course of disease, bone erosion, tumor growth patterns, anesthesia mode, and the surgeon's experience were all extracted, and Cox regression models were used to estimate recurrence rate with adjustment for potential confounders.According to the Cox regression analysis, the recurrence rate after surgery was significantly higher in patients with a diffused form than in those with a localized one (P = 0.001); in addition, patients with 2 or more tumors had a much higher postoperative recurrence rate than did those with only 1 tumor (P = 0.023).This study suggested that the recurrence rate of tenosynovial giant cell tumors of the hand was closely related to the tumor number and tumor growth patterns.

The surgical outcome and recurrence rate of tenosynovial giant cell tumor in the elbow: a literature review

BACKGROUND

Tenosynovial giant cell tumor (TSGCT) is a rare proliferative disorder of the synovium. Because of its aggressive nature and recurrence potential, treatment of TSGCT involves surgical resection with or without synovectomy. There is currently a paucity of literature describing the surgical management of TSGCT at the elbow. The aim of this study was to evaluate clinical outcomes and recurrence rates following open and arthroscopic excision of TSGCT in the elbow.

METHODS

Electronic databases were searched for relevant articles relating to surgical management of TSGCT of the elbow. We included all patients who received surgical treatment for TSGCT, with no age limitations. We excluded any nonsurgical treatment studies. Seventy-seven articles were identified for screening, and a total of 27 patients from 24 studies were included for the review.

RESULTS

The patients' mean (standard deviation [SD]) age was 40.3 (21.7) years, and the most common presenting symptoms included pain (18/27, 66.7%), swelling (19/27, 70.4%), and decreased range of motion of the elbow (9/27, 33.3%). The majority of patients underwent open excision with or without synovectomy (23/27, 85.1%). Of those undergoing open procedures, 16 (16/23,69.6%) had diffuse TSGCT and 14 (14/23, 60.9%) remained symptom free for a mean (SD) follow-up of 38.9 (25.4) months. Four patients (4/27, 14.8%) were treated arthroscopically, all of whom had diffuse disease.

CONCLUSIONS

Our review found that open synovectomy appears to be an effective treatment for both localized and diffuse TSGCT in the elbow, and arthroscopic synovectomy is emerging as a method of surgical management for diffuse TSGCT. However, because of the limited number of patients undergoing surgery for TSGCT, further studies are needed to make a definite conclusion.

Giant Cell Tumor of Soft Tissue: A Rare Entity

Giant cell tumor (GCT) of the soft tissue (GCT-ST) is a rare, unusual primary soft tissue tumor that is completely distinct from, and should not be confused with, any giant cell-rich tumor of bone or soft tissue. Currently, GCT-ST is included in the group of so-called fibrohistiocytic tumors of intermediate (borderline) malignancy. The most common symptom is a painless, slow-growing mass in a superficial location. Computed tomography and magnetic resonance imaging show a solid, nonhomogeneous, frequently hemorrhagic mass. Differential diagnosis is broad and should include benign and malignant entities. The treatment and excision margins of GCT-ST are controversial. Incomplete surgical excision is usually followed by local recurrence. Biological behavior is unpredictable. Giant cell tumor of the soft tissue has shown a lower mean local recurrence rate compared to GCT of bone but has a higher metastatic and death rate. Therefore, close clinical follow-up is recommended. [Orthopedics. 2019; 42(4):e364-e369.].

Histologically benign metastasizing tenosynovial giant cell tumor mimicking metastatic malignancy: A case report and review of literature

Diffuse-type tenosynovial giant cell tumor (D-TGCT), otherwise known as pigmented villonodular synovitis, is a locally aggressive tumor which can show multiple recurrences but is rarely associated with metastasis. A handful of studies have elucidated the imaging features and clinical course in metastatic D-TGCT with malignant transformation on histology. However, only 5 cases of metastatic D-TGCT with benign histological features have been reported in the literature, with the clinical course and prognosis reported in only 1 case. Therefore, relatively little is known about the implications of histologically benign metastasis on the role of imaging, management, and clinical outcomes. We report a case of a 51-year-old female with recurrent D-TGCT localized to the knee that metastasized to the lymph nodes and soft tissue 3 years after above-the-knee amputation and 16 years after initial diagnosis of localized D-TGCT, despite benign histologic features on lymph node excision. This case highlights the necessity of timely MRI imaging to prevent delayed diagnosis, the role of histological findings on treatment response, and clinical outcomes associated with metastasized D-TGCT.

Histiocyte-rich rhabdomyoblastic tumor: rhabdomyosarcoma, rhabdomyoma, or rhabdomyoblastic tumor of uncertain malignant potential? A histologically distinctive rhabdomyoblastic tumor in search of a place in the classification of skeletal muscle neoplasms

Skeletal muscle tumors are traditionally classified as rhabdomyoma or rhabdomyosarcoma. We have identified an unusual adult rhabdomyoblastic tumor not clearly corresponding to a previously described variant of rhabdomyoma or rhabdomyosarcoma, characterized by a very striking proliferation of non-neoplastic histiocytes, obscuring the underlying tumor. Ten cases were identified in nine males and one female with a median age of 43 years (range 23-69 years). Tumors involved the deep soft tissues of the trunk (N = 4), lower limbs (N = 4), and neck (N = 2). Tumors were well-circumscribed, nodular masses, frequently surrounded by a fibrous capsule containing lymphoid aggregates and sometimes calcifications. Numerous foamy macrophages, multinucleated Touton-type giant cells, and sheets/fascicles of smaller, often spindled macrophages largely obscured the underlying desmin, MyoD1, and myogenin-positive rhabdomyoblastic tumor. Cases were wild type for MYOD1 and no other mutations or rearrangements characteristic of a known subtype of rhabdomyoma or rhabdomyosarcoma were identified. Two of four cases successfully analyzed using a next-generation sequencing panel of 170 common cancer-related genes harbored inactivating NF1 mutations. Next-generation sequencing showed no gene fusions. Clinical follow (nine patients; median 9 months; mean 23 months; range 3-124 months) showed all patients received wide excision; four patients also received adjuvant radiotherapy and none received chemotherapy. At the time of last follow-up, all patients were alive and without disease; no local recurrences or distant metastases occurred. We hypothesize that these unusual tumors represent rhabdomyoblastic tumors of uncertain malignant potential. Possibly over time they should be relegated to a new category of skeletal muscle tumors of intermediate (borderline) malignancy.

Malignant Tenosynovial Giant Cell Tumor: The True "Synovial Sarcoma?" A Clinicopathologic, Immunohistochemical, and Molecular Cytogenetic Study of 10 Cases, Supporting Origin from Synoviocytes

We present our experience with ten well-characterized malignant tenosynovial giant cell tumors, including detailed immunohistochemical analysis of all cases and molecular cytogenetic study for CSF1 rearrangement in a subset. Cases occurred in 7 M and 3 F (mean age: 52 years; range: 26-72 years), and involved the ankle/foot (n = 1), finger/toe (n = 3), wrist (n = 1), pelvic region (n = 3), leg (n = 1), and thigh (n = 1). There were eight primary and two secondary malignant tenosynovial giant cell tumors. Histologically, all cases showed definite areas of typical tenosynovial giant cell tumor. The malignant areas varied in appearance. In some cases, isolated malignant-appearing large mononuclear cells with high nuclear grade and mitotic activity were identified within otherwise-typical tenosynovial giant cell tumor, as well as forming larger masses of similar-appearing malignant cells. Occasionally, these nodules of malignant large mononuclear cells showed transition to pleomorphic spindle cell sarcoma, with varying degrees of collagenization and myxoid change. One malignant tenosynovial giant cell tumor was composed of sheets of monotonous large mononuclear cells with high nuclear grade, growing in a hyalinized, osteoid-like matrix, with areas of heterologous osteocartilaginous differentiation. Mitotic activity ranged from 2 to 34 mitoses per 10 HPF (mean 18/10 HPF). Geographic necrosis was observed in four cases. The malignant-appearing large mononuclear cells were consistently positive for clusterin and negative for CD163, CD68, and CD11c. Desmin was positive in a small minority of these cells. Areas in malignant tenosynovial giant cell tumor resembling pleomorphic spindle cell sarcoma or osteo/chondrosarcoma showed loss of clusterin expression. RANKL immunohistochemistry was positive in the large mononuclear cells in eight cases. Two cases showed an unbalanced rearrangement of the CSF1 locus. Follow-up (nine patients; range 0.5-66 months; mean 20 months) showed three patients dead of disease, with three other living patients having lung and lymph node metastases; three patients were disease-free. We conclude that malignant tenosynovial giant cell tumors are highly aggressive sarcomas with significant potential for locally destructive growth, distant metastases, and death from disease. The morphologic and immunohistochemical features of these tumors and the presence of CSF1 rearrangements support origin of malignant tenosynovial giant cell tumor from synoviocytes.

Diffuse-Type Tenosynovial Giant Cell Tumor of the Shoulder Evaluated by FDG PET/CT

Diffuse-type tenosynovial giant cell tumor is a locally aggressive neoplasm that typically involves the knee and hip but rarely involves the shoulder. In this case, a 74-year-old woman presented a painless mass in the right shoulder. FDG PET/CT demonstrated intense FDG uptake with an SUVmax of 19.2 in the lesion. The mass was dissected and confirmed as diffuse-type tenosynovial giant cell tumor by pathology. Follow-up FDG PET/CT assessment revealed more extensive soft tissue infiltration and adjacent bone erosion 3 years after surgery. Thus, FDG PET/CT well demonstrated the hypermetabolic and local aggressive characteristics of the lesion.

Clinical characteristics and treatment outcomes in six cases of malignant tenosynovial giant cell tumor: initial experience of molecularly targeted therapy

Background

Although tenosynovial giant cell tumor (TGCT) is classified as a benign tumor, it may undergo malignant transformation and metastasize in extremely rare occasions. High aberrant expression of CSF1 has been implicated in the development of TGCT and recent studies have shown promising activity of several CSF1R inhibitors against benign diffuse-type TGCT; however, little is known about their effects in malignant TGCT.

Case presentation

Information from six consenting patients (3 men, 3 women) with malignant TGCT presenting to Dana-Farber Cancer Institute for initial or subsequent consultation was collected. Median age at initial diagnosis of TGCT was 49.5 years (range 12–55), and median age at diagnosis of malignant TGCT was 50 years (range 34–55). Two patients developed malignant TGCT de novo, while four other cases showed metachronous malignant transformation. All tumors arose in the lower extremities (3 knee, 2 thigh, 1 hip). Five patients underwent surgery for the primary tumors, and four developed local recurrence. All six patients developed lung metastases, and four of five evaluable tumors developed inguinal and pelvic lymph node metastases. All six patients received systemic therapy. Five patients were treated with at least one tyrosine kinase inhibitor with inhibitory activity against CSF1R; however, only one patient showed clinical benefit (SD or PR). Five patients were treated with conventional cytotoxic agents. Doxorubicin-based treatment showed clinical benefit in all four evaluable patients, and gemcitabine/docetaxel showed clinical benefit in two patients. All six patients died of disease after a median of 21.5 months from diagnosis of malignant TGCT.

Conclusions

This study confirms that TGCT may transform into an aggressive malignant tumor. Lymph node and pulmonary metastases are common. Local recurrence rates are exceedingly high. Conventional cytotoxic chemotherapy showed clinical benefit, whereas tyrosine kinase inhibitors against CSF1R showed limited activity. Given its rarity, a prospective registry of malignant TGCT patients is needed to further understand the entity and to develop effective strategies for systemic treatment.